A touch panel is a human machine interface (HMI) that allows an operator of an electronic device to provide input to the device using an instrument such as a finger, a stylus, and so forth. For example, the operator may use his or her fingers to manipulate images on an electronic display, such as a display attached to a mobile computing device, a personal computer (PC), a terminal connected to a network, and so forth. In some cases, the operator may use two or more fingers simultaneously to provide unique commands, such as a zoom command, executed by moving two fingers away from one another; a shrink command, executed by moving two fingers toward one another; and so forth. In other cases, the operator may use a stylus to provide commands via a touch panel.
A touch screen is an electronic visual display that incorporates a touch panel overlying a display to detect the presence and/or location of a touch within the display area of a screen. The operator can control the display using simple or multi-touch gestures by touching the screen with a stylus and/or one or more fingers. Touch screens are common in devices such as all-in-one computers, tablet computers, satellite navigation devices, gaming devices, and smartphones. A touch screen enables an operator to interact directly with information that is displayed by the display underlying the touch panel, rather than indirectly with a pointer controlled by a mouse or touchpad. The operator can use the touch screen to react to what is displayed and to control how it is displayed. Capacitive touch panels are often used with touch screen devices. A capacitive touch panel generally includes an insulator, such as glass, coated with a transparent conductor, such as indium tin oxide (ITO). As the human body is also an electrical conductor, touching the surface of the panel results in a distortion of the panel's electric field, measurable as change in capacitance.